We have all heard of driving rusty nails into trees (thinking the iron produced the beneficial results), cutting a slit in the bark of the limbs and trunk for "bark bound" so called, etc., all of which have stimulating effects with more or less permanent injury to the tree. Who knows but what the sap sucker, with his ability to dig into the bark and extract a piece of cambium, was not sent to us to aid in preserving our trees by stimulating new growth?
In my work last summer trees that were subjected to slight injury before hand apparently accepted a larger proportion of grafts. I will briefly cite two specific illustrations. A little butternut tree located near the house was the object of my efforts for over two years. During my illness I frequently went out and pruned a few branches or put on a few buds. Something would happen to me and possibly I would not see it again for months, and in the meantime the buds would be strangled or knocked off. Another little hickory tree stood in the roadway. Harrows, plows, wagons and even logs were dragged over it. Grafts on both these trees caught rather readily last spring. In fact two black walnut grafts on this little butternut were two of the very few that I got to grow at all last year. My walnut grafting was almost a total failure. I have this to say, however, that I had no dormant walnut scions, my scions all being cut in May or June.
Mr. Jones, by marking the site of his patch bud several days in advance, admirably carries out this idea by locally stimulating the cambium cells. Dr. Morris's scheme of using white wax, besides regulating sap pressure, allows the actinic rays of the sun to stimulate cellular activity. Cutting the top out of the tree, which disrupts the normal circulation and throws it into the few lower limbs, besides stimulating the cells into activity, has apparently in a large measure accounted for the slight success that I have had. Other methods such as injecting some substance under the bark, applying antiseptics, or some stimulating chemical in a similar way, as "Scarlet Red" is used in skin grafting to increase epithelial growth, may aid materially. Certain chemicals applied to the tree and leaves, as used in sprays, seems sometimes to stimulate growth in a way that can hardly always be accounted for by the checking of the disease for which it was placed.
